Older Women's Stroke Risk Linked to Sleep

July 17, 2008 -- Getting too much sleep may be a more serious sign of stroke risk among older women than not getting enough sleep, according to a new study.

Researchers found that postmenopausal women who slept nine or more hours per night were 70% more likely to suffer an ischemic stroke than women who slept an average of seven hours a night.

An ischemic stroke is the most common type of stroke caused by a blockage in an artery supplying blood to the brain.

In comparison, women who slept six hours or less per night had a 14% higher risk of stroke compared to those who slept seven hours a night.

"What we don't know is whether the longer sleep time was the reason for the increased risk or whether there was some other factor that both led people to sleep more and was also a risk factor for stroke," researcher Sylvia Wassertheil-Smoller, PhD of the Albert Einstein College of Medicine in New York City says in a news release.

"In other words, this study does not mean that if you cut your hours of sleep you would lower your stroke risk. It does mean that people who sleep excessively long hours habitually (or who sleep less than six hours habitually), should discuss this with their doctors and be sure to lower their other risk factors for stroke, especially high blood pressure."

Sleep and Stroke Risk

In the study, published in Stroke: Journal of the American Heart Association, researchers compared sleeping patterns and stroke risk among 93,175 women aged 50 to 79 years.

Although previous studies have provided mixed results on the link between sleep and stroke risk, researchers say some didn't account for other factors that may affect the risk of stroke, such as race, socioeconomic and lifestyle factors, and depression symptoms.

In this study, researchers accounted for known stroke risk factors in analyzing the link between sleep and stroke risk and found an increased risk among those who slept more or less than seven hours per night.

There were 1,166 cases of ischemic stroke over the course of the study (average follow-up of 7.5 years). The lowest risk for stroke was seen in women who slept seven hours a night. The results showed that compared to women sleeping seven hours a night, women who slept nine hours or more had a 70% higher risk of stroke. Those who slept less than six hours per night had a 14% higher risk of stroke. These findings took into account age, race, socioeconomic status, depression, smoking, exercise, use of hormone therapy, and cardiovascular risk factors such as past history or stroke or heart attack, high blood pressure, and diabetes.